SYSTEMATICS AND TAXONOMIC REMARKS ON PINNOTHERES MULINIAR UM RATHBUN, 1918 (CRUSTACEA: BRACHYURA: PINNOTHERIDAE)

C6\Ynpos^^. iqqt^ 8 April 1993 PROC. mol. SOC. WASH. 106(1), 1993, pp. 92-101 SYSTEMATICS AND TAXONOMIC REMARKS ON PINNOTHERES MULINIAR UM RATHBUN, 1918 (CRUSTACEA: BRACHYURA: PINNOTHERIDAE) Ernesto Campos Abstract. The new genus Juxtafabia is proposed to receive the clam crab Pinnotheres muliniarum Rathbun, 1918. The primary diagnostic features are: third maxilliped with carpus and propodus stout, subequal in length; propodus suboblong, with distal end obliquely rounded and a lunate and broad dactylus inserted near its proximal end; and male abdomen widest at somite 3, narrowing at somite 4 which is fused to somite 5, and telson longer than broad. The type species. Pinnotheres muliniarum Rathbun, 1918, described from a pre-hard stage male is considered to be a senior synonym of P. reticulatus Rathbun, 1918, which was described on the basis of an adult female. Description and figures of the young pre-hard stage, adult hard stage male, adult female, complete synonymy, known distribution, and host are presented. Resikmen. El nuevo genero Juxtafabia se propone para recibir al cangrejo almejero Pinnotheres muliniarum Rathbun, 1918. Sus caracteristicas diagnosticas primarias son: tercer maxilipedio con el carpus y propodus iguales en longitud y robustos; el propodus suboblongo tiene su final distal oblicuamente redondeado y lleva proximoventralmente al amplio y lunado dactilus; y el abdomen, en el macho, se ensancha en el somita 3, se adelgaza en el 4 el cual esta fusionado al 5, y con un telson mas largo que ancho. La especie tipo, Pinnotheres muliniarum Rathbun, 1918, que fue descrita en base a un macho en fase predura es aqui considerado como un sinonimo antiguo de P. reticulatus Rathbun, 1918, la cual fue descrita sobre la base de una hembra adulta. Descripcion y figuras de las fases masculinas pre-dura y dura, la hembra adulta, la sinonimia completa, la distribucion conocida y los huespedes para esta especie, se registran. The Pinnotheridae is a group of symbiotic termined that P. jamesi Rathbun, 1923, deand sexually dimorphic crabs that undergo scribed from a hard stage male (sensu Chrisa series of morphological changes during tensen & McDermott 1958) is a junior their postplanktonic development. This has synonym of P. reticulatus'k2l\hhun, 1918, resulted in some mistaken identifications a species which was described on the basis representing developmental stages of the of a post-hard stage female. Postplanktonic same species. For example, Williams (1965) stages of P. reticulatus collected in the upper found that Pinnotheres depressus Rathbun, Gulf of California in 1986-1987 confirmed 1918 was the pre-hard stage male of P. os- Green's conclusions, and a comparison of treum Say, 1817, and Campos (1989b) con- the pre-hard stage male with the holotype eluded that P. pw^^5c^«5 (Holmes, 1894) is of P. muliniarum Rathbun, 1918 revealed a young female of Tumidotheres margarita no difference. In addition, a morphological (Smith, 1869). Recently, Green (1985) de- analysis of these specimens has led to the

VOLUME 106, NUMBER 1 93 proposition of a new genus for this species. This new genus most closely resembles Fabia Dana, 1851. Specimens for this study were obtained from: National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM); Colleccion Carcinologica, Instituto de Biologia, Universidad Nacional Autonoma de Mexico (EM) and Facultad de Ciencias, Universidad Autonoma de Baja California (UABC). The abbreviation cw refers to carapace width. Systematics and Taxonomic Account Remarks. Other genera in the Pinnotheridae which also have the ischium and merus of the third maxilliped indistinguishably fused differ from Juxtafabia as follows: Dissodactylus Smith, 1870, Clypeasterophilus Campos «&, Griffith, 1990, Parapinnixa Holmes, 1894 and Sakaina Serene, 1964 have an exopod without flagellum (Fig. 1 A); Calyptraeotheres Campos, 1990, Ostracotheres H. Milne-Edwards, 1853 and Xanthasia White, 1846 have a palp with two articles (Fig. \W); LimotheresYioXthms, 1975 and Orthotheres Sakai, 1969 have the dactylus inserted distally on the propodus (Fig. IC); Pinnixa White, 1846 and Scleroplax Juxtafabia, new genus Rathbun, 1893 have a lobe on the external Diagnosis. QV[idi\Q carapace subglobu-margilar, dorsal regions weakly defined. Third 1851, Tumidotheres Campos, 1989b, and of the exopod (Fig. ID); Fabia Dana, maxilliped with ischium and merus indistinguishably fused, ventral margin angular, palp with the dactylus inserted on the mid Durckheimia De Man, 1889, have a small dorsal margin gently convex; palp slightly dle of the propodus (Fig. IE); and Pinnotheres Bosc, 1802 s. str. has a linear and slender shorter than ischium-merus, carpus and propodus subequal in length, stout, latter dactylus inserted proximally on the inner article suboblong with distal end obliquely margin of the spatulate propodus (Fig. 1F), rounded, dactylus lunate, broad, ventrally and seven free abdominal somites. Additional differences between Juxtafabia and inserted near proximal end of propodus. Abdomen with 7 free somites, laterally the above genera can be found in Biirger reaching to coxae of walking legs, distally (1895), Rathbun (1918), Tesch (1918), Serene (1964, 1967), Holthuis (1975), Cam covering buccal cavity. Male carapace subglobular, regions weakly defined, pterygostomian region elevated, Griffith (1990). pos (1989a, 1989b, 1990) and Campos & eyes visible in dorsal view; third maxilliped The new genus Juxtafabia most closely similar to that of female; abdomen widest resembles the genus Fabia. Males in both at somite 3, narrowing at somite 4 which is genera have two or more abdominal somites fused to somite 5, telson longer than broad. fused. However, there are no morphological Type species. By present designation and similarities between females of the two genera. Larvae of J. muliniarum resemble zoeae monotypy. Pinnotheres muliniarum Rathbun, 1918. Gender feminine. of Fabia and Pinnixa. Zoeae in these genera Distribution. Upper Gulf of California, have a common pattern of setae on their Mexico to Costa Rica, Central America, appendages, a carapace with moderately developed rostral, lateral and dorsal spines and Hosts. yioxhiscdi, Bivalvia: species of Chione, Polymesoda, Protothaca and Tagelus. share a very distinct lateral and posterior a distinctive abdominal shape. These genera Etymology. Th.Q generic name is derived from the latin Juxta, close to, at side (Fig. 2A-E). The genus Pinnixa, however, expansion oil the fifth abdominal somite of, and the generic name Fabia. The name has an elongated telson which is quite distinct from that in Juxtafabia and Fabia. has been selected to emphasize the resemblance of Juxtafabia and Fabia. Whether these morphological similarities

94 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 1. Third maxilliped. A, Dissodactylus lockingtoni Glassell, 1935; B, Calyptraeotheres granti (Glassell, 1933); C, Orthotheres unguifalcula (Glassell, 1935); D, Scleroplax granulata Rathbun, 1893; E, Fabia sp.; F, Pinnotheres pisum (Linnaeus, 1767). [F, redrawn from Ingle (1980:52, fig. 25)].

VOLUME 106, NUMBER 1 95 Fig. 2. Dorsal view of zoeal abdomen. A, Juxtafabia muliniarum (Rathbun, 1918); B, Fabia subquadrata Dana, 1851; C, Fabia sp.; D, Pinnixa longipes (Lockington, 1877); E, Pinnixa aff. rathbuni Sakai, 1934 [D and E redrawn from Bousquette (1980:596, fig. 4A) and Konichi (1983:282, fig. 14C) respectively].

96 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON between males and larvae have phylogenetic implications remains to be determined. Juxtafabia muliniarum (Rathbun, 1918), new combination Pinnotheres muliniarum Rathbun, 1918:81, pi. 18, figs. 2, 3.-Glassell 1934:301.- Schmitt et al. 1973:5, 10, 58. Campos 1989b:672. Pinnotheres reticulatus Rathbun, 1918:93-94, pi. 21, figs. 1, 2.-Glassell 1934:301; 1935:105.-Schmitt et al. 1973:5, 83.- Green 1985: 611-614, figs. 1, 2.- Campos-Gonzalez 1988:385. Campos 1989b:672. Pinnotheres jamesi Rathbun, 1923:625-626, pi. 29, figs. 1, 2, text-figs. 1, 2.-Glassell 1934:301.-Silas «fe Alagarswami 1967: 1200, 1223.-Schmittetal. 1973:50. Type locality. l^ower California (Baja California, Mexico). Distribution. Gulf of Santa Clara (Gulf of California), Baja California, Mexico to Costa Rica. Hosts. Mollusca, Bivalvia: Chione californiensis (Broderip), C. fructifaga (Sowerby), C. tumens (Verril), Polymesoda inflata (Philippi), Protothaca grata (Say) and Tagelus affinis (C. B. Adams). Material examined. \io\o\y^q of Pinnotheres muliniarum. Lower California, male, cw 3.6 mm (fide Rathbun 1918), USNM 23443. Holotype of P. reticulatus, off" San Jose Island, Baja California Sur, 25 02'15"N, 110 43'30"W, 17 fms (31 m), S.Sh., 17 Mar 1889, Station 3002 Albatross, female, cw 9.2 mm (fide Rathbun 1918), USNM 18217.-1 female, cw 2.9 mm, Gulf of Santa Clara, Baja California, 25 Apr 1990, in Chione fructifaga, UABC 12 ovigerous females, cw 5 to 10 mm, 4 young males, cw 1 to 2.2 mm, Campo El Pescador, on coast 4.5 km North of San Felipe, Baja California, 1988, in Protothaca grata, Chione californiensis and C fructifaga, UABC 7 young males, cw 1 to 2.3 mm, 11 adult males, cw 2.2 to 3.4 mm, and 30 females, cw 4 to 10 mm, Laguna Pecebu, about 23 km south of San Felipe, 1987-88, in P. grata and Tagelus affinis, UABC 1 female, cw 5.7 mm, Puertecitos, km 72 road San Felipe-San Luis Gonzaga, Aug 1986, in P. grata, UABC 1 ovigerous female, cw 10 mm, San Marcos Island, north of La Yesera (27 17'N, 112 07'W), 16 May 1987, in Chione tumens, EM. Male pre-hard stage. Carapace transversely subglobular, soft, posterior margin convex; front slightly projected and strongly deflexed (Fig. 3). Third maxilliped with palp slightly shorter than ischium-merus (Fig. 5A); carpus subequal to propodus in length, latter suboblong, with distal end obliquely rounded; dactylus broad, lunate, ventrally inserted near proximal end of propodus, nearly reaching to distal end of last article. Chelipeds stouter than walking legs, merus widening slightly distally, dorsal margin convex, ventral margin straight; fingers subequal, slightly deflexed, curved at tip where they cross; cutting edge of dactylus with small tooth. Relative length of the walking legs 2 > 3 > 1 > 4, fourth leg not overreaching carpus of third leg; margin of legs hairy, specially on meri; dorsal margin of propodi convex, ventral margin in legs 1-3 straight, concave in leg 4; dactyli 1-3 hook-like; dactylus 4 less curved than on legs 1-3. Abdomen widest at somite 3, narrowing at somite 4, telson longer than broad, distally rounded. Somites 4 and 5 fused. Gonopods simple, curved at base, distally straight (Fig. 5B). Male hard stage. Carapace (Fig. 4) transversely subglobular, well calcified, lateral margins with a heavy fringe of hair-like setae; pterygostomian region higher than in pre-hard stage so that eyes are more conspicuous in dorsal view; frontal region occasionally produced; posterior margin almost straight. Third maxilliped similar to that of male pre-hard stage (Fig. 5C). Chelipeds no more stout than walking legs; i

VOLUME 106, NUMBER 1 97 Fig. 3. Juxtafabia muliniarum (Rathbun, 1918); dorsal view of pre-hard stage male. Carapace length = 2.3 manus widening distally; dorsal margin convex; fingers subequal, curved and crossed at tip; ventral margin almost straight; pollex with 2 acute teeth on proximal half of cutting edge, between them a notch where truncate tooth of dactylus fits. Walking legs stout, dorsal and ventral margin of meri fringed with setae; propodi tapering distally, dorsally convex, almost straight ventrally; dactyli equal to those of pre-hard stage. External face of carpus and propodus of walking legs 2 and 3 with long swimming setae. Abdomen similar to that of pre-hard stage, but somite 7 occasionally subrectangular (Fig. 5D). Fig. 4. Juxtafabia muliniarum (Rathbun, 1918); dorsal view of hard stage male. Carapace length = 3.14 mm. Single setae shown on dorsal and ventral margin of the last walking legs may actually be plumose setae.

98 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 5. Juxtafabia muliniarum (Rathbun, 1918). Pre-hard stage male: A, third maxilliped; B, gonopod. Hard stage male C, third maxilliped; D, abdomen; E, gonopod. F, third maxilliped of last post-hard stage female. [A and C-D redrawn from Rathbun (1918:81, fig. 38, and 1923:626, figs. 1 and 2)]. Gonopods similar to those in pre-hard stage, but longer and slender (Fig. 5E). Female (ovigerous). Carapace (Fig. 6) subglobular, broader than long, soft, slightly convex; gastric region elevated on medial line and separated by broad depression from branchial region; a lunate depression near hepatic margin. Front slightly convex in dorsal view, scarcely projecting beyond curve of anterolateral margin. Eyes globular, completely filling orbits, visible dorsally, cornea evident. Epistome and labium similar in length and width. Antenna with blocky basal articles, flagellum minute, not overreaching upper margin of orbit. Antennulae placed in wide fossettes not larger than orbits. First 2 articles of palp of third maxilliped broad, subequal in length; dactylus curved, lunate, attached proximally and reaching to end of suboblong propodus (Fig. 5F). Chelipeds and legs short, pubescent; chelipeds hairy on inner faces; manus subelliptical, increasing slightly distally, lower mar-

VOLUME 106, NUMBER 1 99 Fig. 6. Juxtafabia muliniarum (Rathbun, 1918); dorsal view of adult female. Carapace length = 7 mm. (Eyes are dorsally visible when abdomen is folded towards carapace sternum). gin straight, upper slightly convex; pubescence arranged in reticulate pattern, the interstices of which are smooth and of darker color (in alcohol); fingers moderately stout, tips hooked toward each other, prehensile edges of each armed with 2 teeth of which that near base of dactylus is largest, other minute teeth between them. Walking legs furnished with long setae on lower margin, specially on propodus of first and fourth leg; relative length of legs 2 > 3 > 4 > 1, the second leg may be asymmetrical, with propodus and dactylus of left leg longer than on right one; ventral margin of propodus of second and third leg concave; ventral margin of propodus of first and fourth leg straight; dactyli 1, 2 and 3 similar, curved and with slender tips, first shortest. second longest; dactylus 4 much longer than those preceding and may be longer than its propodus. Abdomen with 7 free somites, longer and broader than carapace (modified from Rathbun 1918). Remarks. ThQ study of males in hard stage (host, Tagelus affinis) and females in post-hard stage (host, Protothaca grata and T. affinis) collected during the spring and summer of 1986-1987 at Laguna Percebii, south of San Felipe, led to the confirmation of Green's (1985) conclusion that Pinnotheres jamesi is a junior synonym of P. reticulatus. Subsequent collecting of pre-hard stage males (host, Chione californiensis) of a pinnotherid crab from Campo El Pescador showed no difference with Rathbun's (1918)

100 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON holotype of Juxtafabia muliniarum. Examination of additional males collected from T. affinis showed that some specimens represented pre-hard stage males which were identical to those previously identified as /. muliniarum (from El Pescador). The other specimens were hard stage males identical to P. jamesi. To determine whether both types of males examined were conspecific, specimens of pre-hard stage males (=/. muliniarum) were kept alive until they molted to a hard stage identical to those identified as P. jamesi. These results and the study of the complete postplanktonic female stages from San Felipe and vicinity, led to the conclusion that J. muliniarum, P. jamesi and P. reticulatus represent the same species. Juxtafabia muliniarum was the first named species and, therefore, is the senior synonym of the other two taxa. Acknowledgments Many thanks to Prof. A. Carvacho for allowing me to revise the holotypes of J. muliniarum and P. reticulatus which were kindly loaned to him by Dr. R. B. Manning (Smithsonian Institution). I also thank Prof. Carvacho and J. F. Bergerault for loaning additional specimens of/, muliniarum. My deep gratitude goes to my wife Alma Rosa for hard field and laboratory work, for preparing original figures, and for commenting on early manuscript versions and most importantly for continued encouragement to see this paper to completion. This work was partially supported by the program "Sistematica de Crustaceos" of the Facultad de Ciencias, Universidad Autonoma de Baja California and by agreements SEP-UABC 087-01-0426 and 089-01-0352 and CONACyT 0482-N9108. Literature Cited Bosc, L. A-G. 1802. Histoire naturelle des Crustaces, contenant leur description et leurs moeurs, avec figures dessinees d'apres nature. Deterville, Paris, 1:1-258, pis. 1-8. Bousquette, G. D. 1980. The larval development of Pinnixa longipes (Lockington, 1877) (Brachyura, Pinnotheridae) reared in the laboratory. Biological Bulletin 159:592-605. Burger, O. 1895. Ein Beitrag zur Kenntniss der Pinnotherinen. Zoologische Jahrbiicher, Abtheilung fiir Systematik, Geographic und Biologic der Thiere 8:361-390. Campos, E. 1989a. Comments on taxonomy of the genus Orthotheres Sakai, 1969 (Crustacea, Brachyura, Pinnotheridae). Bulletin of Marine Science 44(3):1123-1128.. 1989b. Tumidotheres di ntvi g&nxis ior Pinnotheres margarita Smith, 1869, and Pinnotheres maculatus Say, 1818 (Brachyura: Pinnotheridae). Journal of Crustacean Biology 9:672-679.. 1990. Calyptraeotheres, a ne^w gennsoivinnotheridae for the limpet crab Fabia granti Glassell, 1933 (Crustacea, Brachyura). Proceedings of the Biological Society of Washington 103:364-371.,&H.Griffith. 1990. Clypeasterophilus,anew genus to receive the small-palped species of the Dissodactylus complex (Brachyura: Pinnotheridae). Journal of Crustacean Biology 10:550-553. Campos-Gonzalez, E. 1988. New molluscan hosts for two shrimps and two crabs on the coast of Baja California, with some remarks on distribution.-the Veliger 30:384-386. Christensen, A. M., & J. J. McDermott. 1958. Lifehistory and biology of the oyster crab. Pinnotheres ostreum Say. Biological Bulletin 114:146-179. Dana, J. D. 1851. On the classification of the Crustacea Grapsoidea. American Journal of Science and Arts, series 2, 12:283-291. De Man, J. G. 1889. Ueber einige oder seltene Indopacifische Brachyuren. Zoologische Jahrbiicher, Abtheilung fiir Systematik, Geographic und Biologic der Thiere 4:409-452. Glassell, S. A. 1933. Description of five new species of Brachyura collected on the west coast of Mexico. Transactipns of the San Diego Society of Natural History 7:331-334.. 1934. Affinities of the brachyuran fauna of the Gulf of California. Journal of Washington Academy of Science 24:296-302.. 1935. New or little known crabs from the Pacific coast of Northern Mexico. Transaction of the San Diego Society of Natural History 8:91-106. Green, T.M. 1985. Pinnotheres jamesi synonymiztd with P. reticulatus (Decapoda: Brachyura). Proceedings of the Biological Society of Washington 98:611-614.

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